Just yesterday here we shared a bunch of XF8-16 and GF250 prototype images.
Now also ephotozine uploaded their sample images of the prototypes, and they show the XF8-16 next to the XF 16mm.
Please note that the XF16mm has the rear cap mounted on it, whereas the XF8-16 has no rear cap, which makes the XF16mm a bit longer than it should be.
There are many more images to see at ephotozine here.
They also shared GF250mm hands on photos here.